Poly(ADP-ribose)polymerase-1 (PARP-1) a nuclear enzyme bounded to chromatin involved in a variety of physiological functions related to genomic repair, including DNA replication and repair, cellular proliferation and differentiation, and apoptosis. Inhibition of these PARP enzyme results in genomic dysfunction and finally leading to cell death (Ferraris, D. V. J. Med. Chem. 2010, 53, 4561).
Quinazolinone (1) is a naturally occurring alkaloid as well as a core structural subunit in a growing class of bioactive natural products and synthetic compounds (Michael, J. P. Nat. Prod. Rep. 2004, 21, 650” and also D'yakonov, A. L.; Telezhenetskaya, M. V. Chem. Nat. Comput. 1997, 33, 221). Recently various quinazolinone compounds were identified as dual inhibitors of P-glycoprotein (Pgp) and the multidrug resistance associated protein (MRP1). These proteins cause resistance in tumor cells hence inhibition of these proteins were useful in cancer chemotherapy (Wang, S.; Ryder, H.; Pretswell, I.; Depledge, P.; Milton, J.; Hancox, T. C.; Dale, I.; Dangerfield, W.; Charlton, P.; Faint, R.; Dodda, R.; Hassan, S. Bioorg. Med. Chem. Lett. 2002, 12, 571). Recently a library of quinazollinone compounds containing 2-styryl quinazolinone compounds possessing a defining structural feature, containing 3-substituted aliphatic chain bearing basic nitrogen, exhibiting cytotoxicity against various cancer cell lines. (Liu, J. F.; Kaselj, M.; Isome, Y.; Ye, P.; Sargent, K.; Sprague, K.; Chemak, D.; Wilson, C. J.; Si, Y.; Yohannes, D.; Ng, S. C. J Comb Chem. 2006, 8, 7-10). Various substituted 2-phenyl-4-quinazolinones and 2,3-dihydro-2-phenyl-4-quinazolinones displayed highly selective cytotoxicity against the ovarian cancer 1A9 and P-gp resistant KB-VIN cell lines and these compounds acts as tubulin polymerization inhibitiors. (Hour, M. J.; Huang, L. J.; Kuo, S. C.; Xia, Y.; Bastow, K.; Nakanishi, Y.; Hamel, E.; Lee, K. H. J. Med. Chem. 2000, 43, 4479). Moreover a new class of 4(3H)-quinazolinones 2-styryl substituted derivatives (2) form an important component of pharmacologically active compounds which exhibit anticancer activity by inhibition of tubulin polymerization. (Jiang, J. B.; Hesson, D. P.; Dusak, B. A.; Dexter, D. L.; Kang, G. J.; Hamel, E. J. Med. Chem. 1990, 33, 1721″ and also Raffa, D.; Edler, M. C.; Daidone, G.; Maggio, B.; Merikech, M.; Plescia, S.; Schillaci, D.; Bai, R.; Hamel, E. Eur. J. Med. Chem. 2004, 39, 299). Whereas a novel series containing 2-methyl quinazolinones and 2-aryl quinazolinones act as inhibitors of DNA repair enzyme poly (ADP-ribose) polymerase. (Griffin, R. J.; Srinivasan, S.; Bowman, K.; Calvert, A. H.; Curtin, N. J.; Newell, D. R.; Pemberton, L. C.; Golding, B. T. J. Med. Chem. 1998, 41, 5247).
Recently a series of 3-aryl ethynyl substituted quinoline-8-carboxamide were synthesized and identified as a new class of PARP inhibitors. (Lord, A. M.; Mahon, M. F.; Lloyd, M. D.; Threadgill, M. D. J. Med. Chem. 2009, 52, 868-877) and also a new series of 3-ethynyl-1H-indazoles (3) has been synthesized and exhibited low micro molar inhibition against critical components of the PI3K pathway, targeting PI3K, PDK1, and mTOR kinases, These compound displays significant antiproliferative activity both in monolayer human cancer cell cultures and in three dimensional tumor models and these identified as multiple PI3K/PDK1/mTOR inhibitors. (Barile, E.; De, S. K.; Carlson, C. B.; Chen, V.; Knutzen, C.; Riel-Mehan, M.; Yang, L.; Dahl, R.; Chiang, G.; Pellecchia, M.). More recently structure-activity relationship study revealed the rigid triple bond functionality also contributed to the observed antiviral activity and also antiproliferative activity for ethynyltriazole ribonucleosides which are showing potent a poptosis-induced antiproliferative activity against pancreatic cancer MiaPaCa-2 cells both in vitro and in vivo The role of ethynyl group may be due to appended π-conjugated systems to offer helpful binding properties with the corresponding biological targets via the stronger interactions afforded by a larger aromatic binding surface and better shape complementary conjugated system. (Wan J, Xia Y, Liu Y, Wang M, Rocchi P, Yao J, Qu F, Neyts J, Iovanna J L, Peng L. J. Med. Chem. 2009, 52, 1144-1155).
Keeping this aspect in mind, various aryl ethynyl groups are incorporated at N-3 position of quinazolinones. Further structural modifications have also been carried out at position 2 of quinazolinone ring. Thereby, the newly designed and synthesized molecules comprising of quinazolinone and phenyl ethynyl moiety could possess promising anticancer activity that might work through inhibition of PARP. Additionally, these are structurally simple small molecules.
